Investigation on displacement efficiency and enhance oil recovery performance of CO2 and CO2-chemical additive composite system flooding using LBM simulation

•Novel Approach: The study introduced a new approach for characterizing the CO2-chemical additive composite system.•Miscibility and Viscosity Effects: The investigation highlighted the significance of miscibility and viscosity in CO2-chemical additive composite system flooding.•Optimization Opportunities: This study further improves the CO2 utilization rate and its various factors.•Practical Implications: The research outcomes have practical implications for the field application of chemical additives to enhance the effectiveness of CO2 flooding.